Chromium-nickel austenitic stainless steels are
prone to this form of corrosion when they are
welded and subsequently in contact with
certain types of corrosive media. When heated
within a temperature range of 450-800 deg C
precipitation of the chromium carbides takes
place at the grain boundaries in the area of the
weld and these areas no longer have the
protection of the chromium on the peripheries
of the grains. This type of corrosion is also
known as Weld Decay and Intergranular
Corrosion. The most common way to avoid the
problem is to select a grade of steel that is
very low in carbon i.e. 0.03% or less, or one
that is stabilised with niobium or titanium.